Brad Watson screwed up, there is no disputing that.
He blew the whistle while the puck wasn't covered, and I'm sure that he will be the first to admit the whistle shouldn't have been blown. He did however make the right call in ruling it no goal.
NHL Officials are taught that if they blow the whistle because they believe the puck is covered, even if the puck is in before the whistle, they are to rule it no goal. That is what Watson did.
As a hockey official myself, I know that Watson was out of position to be making that call. He was too far in the corner, and he needed to be much closer to the net to make that call.
That being said, officials will get caught out of position, that is a given. The game is so fast and happens so quickly that most times the officials are just trying to stay out of the way of the play, and maintaining positioning becomes a second priority.
Officials are going to get caught out of position, Watson just managed to get caught and blow a call that cost Detroit tying the game.
I really feel for Watson. He really screwed up here, and myself being an on-ice official, in hockey I too have cost teams games, but not quite on the same scale of Watson.
If Detroit loses this series there will be people who will say its not because Anaheim's forwards were better, or because Hiller was the better goaltender, but because Watson screwed them in this game tonight.
No matter how much this one call means to this one game, there is no way you can blame a Detroit series loss on this one call.